Umm, let's say that Antarctica was a land mass where all the snow/ice "covering it" was below sea level and it came up to exactly sea level (like some god had taken a big knife and it cut if off there). Now let's say all of that snow/ice melts. Will the the surrounding ocean level rise, fall, or stay the same? Since snow/ice is just frozen water, and solid water is less dense than liquid water (that's why it rises to the surface), it seems to me that the snow/ice that turned into water would take up less room (would be more dense) than the snow/ice. Therefore, the ocean level would go down slightly. It would not be enough to counteract all the snow/ice that is currently covering the land mass of Antarctica if that were all to melt and flow into and thus raise the sea level. But be that as it may, the original poster is kind of correct when he stated:
"All ice that is currently below the current sea level is irrelevant in determining what happens to the sea level lF IT ALL MELTED." <= It isn't totally irrelevant, since the melting of ice below sea level would contribute to lowering sea level
"Why, as solid ice ..... if it is now below sea level, then if it melts it takes up no more room that it presently is ALREADY DISPLACING." <= that is a correct statement, in fact it actually will take up less room
"An example of how irrational the current science community can be."
I don't know that scientist don't know this. I suspect that good scientists do. So I don't really agree with the posters initial statement, unless it turns out the current science community doesn't realize this...